CDK5 and Primary microcephaly: Rs13301996 is intronic to CDK5RAP2, which encodes a regulator of CDK5 activity (59), interacts with CDK5R1 and pericentrin (PCNT) (59), plays a role in centriole engagement and microtubule nucleation (60) and has been linked to primary microcephaly and Alzheimer’s disease (61,62).